From 9bd984058088d6ef7af6946591a207e51a2f4890 Mon Sep 17 00:00:00 2001 From: Andi Kleen Date: Thu, 12 Feb 2009 13:39:28 +0100 Subject: [PATCH] x86, mce: always use separate work queue to run trigger Impact: Needed for bug fix in next patch This relaxes the requirement that mce_notify_user has to run in process context. Useful for future changes, but also leads to cleaner behaviour now. Now instead mce_notify_user can be called directly from interrupt (but not NMI) context. The work queue only uses a single global work struct, which can be done safely because it is always free to reuse before the trigger function is executed. This way no events can be lost. Signed-off-by: Andi Kleen Acked-by: Thomas Gleixner Signed-off-by: H. Peter Anvin --- arch/x86/kernel/cpu/mcheck/mce_64.c | 25 ++++++++++++++++++------- 1 file changed, 18 insertions(+), 7 deletions(-) diff --git a/arch/x86/kernel/cpu/mcheck/mce_64.c b/arch/x86/kernel/cpu/mcheck/mce_64.c index 25ccdbec86e..18b379cf061 100644 --- a/arch/x86/kernel/cpu/mcheck/mce_64.c +++ b/arch/x86/kernel/cpu/mcheck/mce_64.c @@ -380,11 +380,17 @@ static void mcheck_timer(struct work_struct *work) schedule_delayed_work(&mcheck_work, next_interval); } +static void mce_do_trigger(struct work_struct *work) +{ + call_usermodehelper(trigger, trigger_argv, NULL, UMH_NO_WAIT); +} + +static DECLARE_WORK(mce_trigger_work, mce_do_trigger); + /* - * This is only called from process context. This is where we do - * anything we need to alert userspace about new MCEs. This is called - * directly from the poller and also from entry.S and idle, thanks to - * TIF_MCE_NOTIFY. + * Notify the user(s) about new machine check events. + * Can be called from interrupt context, but not from machine check/NMI + * context. */ int mce_notify_user(void) { @@ -394,9 +400,14 @@ int mce_notify_user(void) unsigned long now = jiffies; wake_up_interruptible(&mce_wait); - if (trigger[0]) - call_usermodehelper(trigger, trigger_argv, NULL, - UMH_NO_WAIT); + + /* + * There is no risk of missing notifications because + * work_pending is always cleared before the function is + * executed. + */ + if (trigger[0] && !work_pending(&mce_trigger_work)) + schedule_work(&mce_trigger_work); if (time_after_eq(now, last_print + (check_interval*HZ))) { last_print = now; -- 2.11.4.GIT